KR101887052B1 - Method for producing rutile-type titanium oxide sol - Google Patents

Abstract

[PROBLEMS] To provide a method for efficiently producing a rutile titanium oxide sol having an excellent dispersibility and a particle diameter of 5 to 100 nm measured according to a dynamic light scattering method. [MEANS FOR SOLVING PROBLEMS] A method for producing a rutile titanium oxide sol having a particle diameter of 5 to 100 nm, which is measured by a dynamic light scattering method including the following steps (a) and (b): (a) Titanium alkoxide, oxalic acid, quaternary ammonium hydroxide and water are mixed, and at that time, the proportion of the oxalic acid in the proportion of 0.1 to 0.8 mol, the proportion of the oxalic acid in the amount of 0.01 to 5 mol, Containing aqueous solution of 0.1 to 15 mass% in terms of TiO ₂ is prepared by adjusting the quaternary ammonium hydroxide to a ratio of 0.1 to 3.5 mol, (b) a step of: preparing a titanium-containing aqueous solution obtained in the step (a) And a hydrothermal treatment at 100 to 200 ° C.

Description

METHOD FOR PRODUCING RUTILE-TYPE TITANIUM OXIDE SOL [0002]

The present invention relates to a process for producing a rutile titanium oxide sol.

There are three types of crystal structures of titanium oxide: rutile type of tetragonal high temperature type, anatase type of tetragonal low temperature type and anatase type of orthorhombic bourcite type. Among them, rutile type titanium oxide has a high refractive index, .

In order to use it as an optical material, it is necessary not only to have a high refractive index, but also to have transparency as a coating film. However, in general, since the rutile titanium oxide is produced by the solid-phase method in which amorphous titanium oxide or anatase-type titanium oxide is baked at a high temperature, there is a problem that the particle diameter becomes large and transparency is impaired.

Compared with the solid-phase method requiring high-temperature firing, the wet method is an easy method for obtaining fine particles because it can be synthesized at a low temperature. As a method for producing a rutile titanium oxide sol by a wet method, there is a method of reacting the titanium salt in the presence of a tin compound having a rutile structure.

As a method of using a titanium salt and a tin compound, there is disclosed a method of reacting a strong acid of titanium with metal tin in the presence of hydrogen peroxide to produce an aggregate of a titanium oxide-tin oxide composite colloid at 50 to 100 ° C 1). Also disclosed is a method for producing rutile titanium oxide fine particles in which a titanium compound solution is allowed to react in a pH range of 1 to 3 at a temperature of from room temperature to 100 ° C in the presence of a tin compound having a Sn / Ti molar ratio of 0.001 to 2 Patent Document 2). As a method of reacting a gel containing titanium atoms dissolved in hydrogen peroxide, a method of dissolving a hydrated titanium oxide gel in hydrogen peroxide and cationically exchanged potassium citrate are mixed and subjected to a heat treatment (see Patent Document 3) A method of reacting a tin compound with ammonia to produce a gel, dissolving it in hydrogen peroxide and hydrothermally treating it (see Patent Document 4), and the like.

Japanese Patent Application Laid-Open No. 10-245224 Japanese Patent Application Laid-Open No. 2005-132706 Japanese Patent Application Laid-Open No. 2-255532 Japanese Patent Application Laid-Open No. 2009-227519

In the method described in Patent Document 1, an agglomerate slurry of titanium oxide-tin oxide composite colloidal particles having a primary particle diameter of 2 to 20 nm is produced, so that it is necessary to remove an electrolyte contained in order to obtain a good sol in a dispersed state . In the method described in Patent Document 2, since a precipitate is formed, a solid-liquid separator is required. In the method described in Patent Document 3, it is difficult to stably prepare a gel or sol of hydrated titanium oxide having a high specific surface area, there is a problem that the crystallinity of the obtained titanium oxide fluctuates. In addition, Impurities such as alkali remain in the sol, so that the resulting rutile-type titanium oxide has a drawback that substantially no alkali-containing substance can be obtained. In the method described in Patent Document 4, it is essential to clean the mixed gel of titanium hydroxide and tin hydroxide. However, since it is difficult to remove impurity ions, a long time is required for cleaning, and a solid-liquid separator is required, .

Accordingly, the present invention provides a method for producing a liquid crystal display device which does not contain substantially alkali metals such as sodium and potassium and impurities such as chlorine, does not require a solid-liquid separation step and is excellent in dispersibility, And a method for efficiently producing a rutile-type titanium oxide sol having a particle diameter of 100 nm to 100 nm.

DISCLOSURE OF THE INVENTION The present inventors have intensively studied to solve the above problems and found that a titanium-containing aqueous solution containing a tin salt is hydrothermally treated in the presence of oxalic acid and a quaternary ammonium hydroxide to form a rutile type It was found that titanium oxide sol can be produced. That is,

As a first aspect, a process for producing a rutile titanium oxide sol having a particle diameter of 5 to 100 nm, which is measured by a dynamic light scattering method comprising the following steps (a) and (b)

(a) Process: A tin oxalate aqueous solution, a titanium alkoxide, oxalic acid, a quaternary ammonium hydroxide and water are mixed, and then 0.1 to 0.8 mol of tin atoms per mol of the titanium atom, 0.01 To 5 moles of said quaternary ammonium hydroxide and 0.1 to 3.5 moles of said quaternary ammonium hydroxide to prepare a titanium-containing aqueous solution having a concentration of 0.1 to 15 mass% in terms of TiO ₂ ,

(b): a step of subjecting the titanium-containing aqueous solution obtained in the step (a) to a hydrothermal treatment at 100 to 200 캜,

As a second aspect, the titanium alkoxide is represented by the general formula (I)

_{^{Ti (OR 1) 4 (I}} )

A process for producing a rutile-type titanium oxide sol according to the first aspect, which is a tetraalkoxytitanium represented by the formula (I) wherein each R ¹ is the same or different and is an alkyl group having 1 to 3 carbon atoms,

As a third aspect, the quaternary ammonium hydroxide is represented by the general formula (II)

[NR ² R ³ R ⁴ R ⁵ ] OH (II)

R ² , R ³ , R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group having 1 to 8 carbon atoms or a carbon number of 7 to 15 An aryloxyalkyl group or a benzyl group], a process for producing a rutile-type titanium oxide sol described in the first aspect,

As a fourth aspect, there is provided a process for producing a rutile titanium oxide sol described in the third aspect, wherein the quaternary ammonium hydroxide is tetramethylammonium hydroxide or tetraethylammonium hydroxide,

to be.

The rutile titanium oxide sol obtained by the process for producing a rutile titanium oxide sol of the present invention does not substantially contain impurities such as alkali metals such as sodium and potassium and chlorine, and has high transparency. Further, the dried coating exhibits a high refractive index of about 1.9 or more, and is excellent in water resistance, moisture resistance, light resistance, weather resistance, heat resistance, wear resistance and the like.

The rutile titanium oxide sol obtained by the process for producing a rutile titanium oxide sol of the present invention can be used as a coating composition by mixing various binders. By applying the composition to a substrate, It is possible to form a coating film having high transparency and high refractive index.

In the present invention, in step (a), an aqueous tin oxalate solution, titanium alkoxide, oxalic acid, quaternary ammonium hydroxide and water are mixed to prepare a titanium-containing aqueous solution. The order of mixing tin oxalate aqueous solution, titanium alkoxide, oxalic acid, quaternary ammonium hydroxide and water is not particularly limited.

The aqueous tin oxalate solution, titanium alkoxide, oxalic acid and quaternary ammonium hydroxide to be mixed are mixed in a ratio of 0.1 to 0.8 mol of tin atoms, 0.01 to 5 mol of oxalic acid, And the hydroxide is adjusted to a ratio of 0.1 to 3.5 mol.

The tin atom is adjusted so as to have a ratio of 0.1 to 0.8 mol per 1 mol of the titanium atom. When the proportion of tin atoms is less than 0.1 per mole of titanium atoms, the crystallinity of the rutile titanium oxide becomes insufficient and anatase-type titanium oxide may be produced in some cases. When the ratio of the tin atoms to one mole of the titanium atom is more than 0.8, the content of tin oxide in the obtained rutile titanium oxide sol is increased, so that the refractive index of the titanium oxide is lowered.

The oxalic acid is adjusted so as to be in a proportion of 0.01 to 5 mol per 1 mol of the titanium atom. When the proportion of oxalic acid is less than 0.01 mol based on 1 mol of the titanium atom, anatase-type titanium oxide is partially formed after the hydrothermal treatment in the step (b), and the target single-phase rutile titanium oxide sol can not be obtained. When the proportion of oxalic acid exceeds 5 moles per 1 mole of titanium atoms, the pH of the titanium-containing aqueous solution becomes less than 3, and the particle diameter measured by the dynamic light scattering method after the hydrothermal treatment in the step (b) A suspension of rutile-type titanium oxide colloid particles in excess can be obtained, and a target rutile-type titanium oxide sol can not be obtained.

The quaternary ammonium hydroxide is adjusted to have a ratio of 0.1 to 3.5 mol per 1 mol of titanium atom. When the proportion of the quaternary ammonium hydroxide is less than 0.1 mol per 1 mol of the titanium atom, the rutile-type titanium oxide colloid particles having a particle diameter of more than 100 nm measured by the dynamic light scattering method after the hydrothermal treatment in the step (b) A suspension is obtained, and the intended rutile-type titanium oxide sol can not be obtained. When the proportion of the quaternary ammonium hydroxide exceeds 3.5 mol per 1 mol of the titanium atom, brittle titanium oxide is produced in addition to the rutile titanium oxide after the hydrothermal treatment in the step (b), and the single-phase rutile type oxidation Titanium sol can not be obtained.

The titanium-containing aqueous solution may be prepared by appropriately adjusting the amount of water to be used so that the concentration in terms of TiO ₂ is 0.5 to 15% by mass. Here, in terms of TiO ₂ is, for convenience as will showing the Ti content in the hydrolytic polymerization chukmul to its oxide in the form of TiO _2, it shows that the number of moles of titanium alkoxide TiO ₂ is contained in the hydrolysis and condensation system.

It is preferable that the above-mentioned aqueous tin oxalate solution, titanium alkoxide, oxalic acid, quaternary ammonium hydroxide and water are mixed under stirring. The obtained titanium-containing aqueous solution may be heated at 60 to 100 占 폚 before hydrothermal treatment of the step (b).

The pH of the titanium-containing aqueous solution prepared by the step (a) is 3.0 to 14.0.

The aqueous tin oxalate solution used in the present invention can be obtained by reacting metallic tin, oxalic acid and hydrogen peroxide in an aqueous medium. The preparation of the aqueous solution of tin oxalate is preferably carried out by intermittently adding a small amount of hydrogen peroxide and metal tin alternately or continuously to maintain the H ₂ O ₂ / Sn molar ratio at 2 to 3 in an aqueous solution of oxalic acid. First, when the entire amount of hydrogen peroxide is added to the aqueous oxalic acid solution and the metal tin is added thereto, most of the hydrogen peroxide is decomposed at an early stage of the reaction and the amount of hydrogen peroxide is insufficient. Even if the molar ratio of H ₂ O ₂ / Sn exceeds 3, the reaction is possible, but the amount of hydrogen peroxide is increased, which is not preferable. If the molar ratio of H ₂ O ₂ / Sn is less than 2, the oxidation becomes insufficient, and desired tin oxalate aqueous solution can not be obtained. The reaction may be carried out under heating or in a range of 30 to 70 캜. The Sn concentration in the reaction liquid is preferably maintained at 0.01 to 8% by mass, and as the finally obtained aqueous tin oxalate solution, the Sn concentration is preferably 1 to 5% by mass. Since the obtained aqueous solution of tin oxalate may contain hydrogen peroxide in some cases, it is preferable to pass hydrogen peroxide through a column packed with an oxidation catalyst carrying platinum.

As the titanium alkoxide used in the present invention, tetraalkoxytitanium having 1 to 3 carbon atoms in the alkoxyl group is used. The tetraalkoxytitanium is represented by the general formula (I)

_{^{Ti (OR 1) 4 (I}} )

[Wherein each R ¹ in formula (I) is the same or different and is an alkyl group having 1 to 3 carbon atoms].

The above tetraalkoxytitanium may be the same or different from the four alkoxyl groups, but the same one is preferably used from the viewpoint of availability and the like. Specific examples of the tetraalkoxytitanium include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium and tetraisopropoxytitanium. These may be used singly or in combination of two or more.

The quaternary ammonium hydroxide used in the present invention is a quaternary ammonium hydroxide represented by the general formula (II)

[NR ² R ³ R ⁴ R ⁵ ] OH (II)

R ² , R ³ , R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group having 1 to 8 carbon atoms or a carbon number of 7 to 15 Quot; represents an aryloxyalkyl group or a benzyl group of "

Specific examples of the quaternary ammonium hydroxides include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, octyltrimethylammonium hydroxide, tributylmethylammonium hydroxide, trioctylmethylammonium hydroxide, benzyltrimethylhydroxide Ammonium benzyl triethyl ammonium hydroxide, benzyltripropyl ammonium hydroxide, benzyl tributyl ammonium hydroxide, ammonium monomethyl triethanol hydroxide, dimethyl diethanol ammonium hydroxide and the like. Among them, tetramethylammonium hydroxide and tetraethylammonium hydroxide are preferably used.

In the step (a), the titanium alkoxide added is decomposed to generate an alcohol. The alcohol of the by-product may be removed without removing it. In the case of removing the alcohol, the titanium-containing aqueous solution may be heated to the boiling point or higher of the alcohol, or may be distilled off under reduced pressure using an evaporator or the like.

The titanium-containing aqueous solution obtained in the step (a) is filled in a pressure-resistant vessel in the step (b) and subjected to hydrothermal treatment. The hydrothermal treatment temperature is from 100 to 200 ° C, preferably from 120 to 180 ° C. The hydrothermal treatment time is 0.5 to 10 hours, preferably 1 to 6 hours. If the temperature for hydrothermal treatment is less than 100 ° C, crystallization of the titanium oxide particles becomes insufficient, and rutile titanium oxide colloid particles can not be obtained. In addition, when the water-heat treatment temperature exceeds 200 ° C, the resulting titanium oxide particles aggregate, so that it is not preferable to obtain a sol without a dispersion treatment using a homogenizer or the like.

In the ICDD card (Invention Center for Diffraction Data) used for powder X-ray diffraction analysis, the plane interval d (Å) of the <110> plane of the tin oxide was 3.35 and the d of the <110> plane of the rutile titanium oxide was 3.25 to be. The rutile titanium oxide sol obtained by the present invention is a single phase rutile crystal in which the diffraction pattern by powder X-ray diffraction analysis and d of the <110> crystal face are in the range of 3.25 <d <3.35.

The rutile-type titanium oxide sol obtained by the present invention can be observed as an elliptic spherical colloid particle having a primary particle diameter of 5 to 50 nm as a projected image in a transmission electron microscope. The obtained rutile titanium oxide sol has a particle diameter of 5 to 100 nm as measured by a dynamic light scattering method particle diameter measuring apparatus. In addition, the rutile titanium oxide sol has high transparency, and no sediment is observed even if it is left at room temperature for one week. The pH of the rutile titanium oxide sol is in the range of 3.0 to 14.0.

The rutile-type titanium oxide sol obtained by the present invention can be cleaned and / or concentrated using an ultrafiltration method.

The rutile-type titanium oxide sol obtained by the present invention can be stabilized as a sol by adding an acid and / or a basic compound, if necessary.

As the acid to be used, inorganic acids such as hydrochloric acid and nitric acid, oxalic acid, lactic acid, tartaric acid, malic acid, citric acid, glycolic acid, hydroacrylic acid, a-oxybutyric acid, glyceric acid and tartronic acid can be used.

Examples of the basic compound to be used include ammonia, an alkali metal hydroxide, ethylamine, diethylamine, n-propylamine, isopropylamine, diisopropylamine, dipropylamine, n-butylamine, isobutylamine, diisobutylamine , Alkylamines such as triethylamine and benzylamine, alkanolamines such as monoethanolamine and triethanolamine, quaternary ammonium hydroxides such as guanidine hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide, and ammonium hydroxides such as ammonium carbonate, And carbonates such as guanidine carbonate.

The rutile titanium oxide sol obtained by the present invention can be mixed with various binders to form a coating composition.

Further, the above-mentioned coating composition may be applied to a substrate to obtain a member having a high refractive index coating. The substrate may be made of various materials such as plastic, rubber, glass, metal, ceramics and paper.

The refractive index of the coating varies depending on the blending ratio of the rutile titanium oxide sol and the binder and the kind of the binder, but is in the range of approximately 1.55 to 2.2.

The coating having a high refractive index obtained by applying the coating composition comprising the rutile titanium oxide sol obtained by the present invention and the binder can impart an antireflection function by further providing an antireflection film.

Example

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

The apparatus used for measurement and observation is as follows.

[Measurement of particle diameter by dynamic light scattering method]

N4PLUS (manufactured by BECKMAN COLUTER)

[Transmission electron microscope observation]

JEM-1010 (manufactured by JEOL Ltd.)

(Production Example 1)

849 g of pure water was placed in a 2 L vessel, and 100 ml of oxalic acid dihydrate [Ube Industries, Ltd. Product] was dissolved in 82 g. Then, a metal tin powder [Yamaishi Metal Co., Ltd. Product] and 35% aqueous hydrogen peroxide solution [manufactured by Kanto Chemical Co., Inc. Product] were each divided into 10 parts, put in alternation, and maintained at 50 to 55 ° C for 2 hours. Subsequently, the excess hydrogen peroxide was removed by passing through a column packed with a platinum catalyst to prepare 1000 g of a tin oxalate aqueous solution having a SnO ₂ concentration of 2.8 mass%. As a result of CHN elemental analysis, the resulting oxalic acid aqueous solution had a concentration of oxalic acid of 4.7 mass%. As a result of the atomic absorption analysis, the sodium concentration was below the quantitative limit (less than 10 ppb).

(Example 1)

26.0 g of tin oxalate aqueous solution (0.75 g in terms of SnO ₂ , containing 1.26 g in terms of oxalic acid) prepared in Production Example 1 and 14.2 g of titanium tetraisopropoxide (containing 4.0 g in terms of TiO ₂₎ g, Kanto Chemical Co., Inc. Product] and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide [product of Tama Chemicals Co., Ltd.] Were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 0.28, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 2.0. 100 g of the titanium-containing aqueous solution was heated at 80 DEG C for 2 hours. The pH of the titanium-containing aqueous solution after heating was 14.0, the conductivity was 64.2 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The resulting sol had a particle diameter of 37 nm as measured by a dynamic light scattering method at a pH of 14.0, a conductivity of 76.3 mS / cm, a concentration of 4.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 9.1 mass%, an oxalic acid concentration of 1.3 mass% In the microscopic observation, circular particles of 20 to 30 nm were observed. The obtained sol was dried at 110 占 폚 and the powder obtained was analyzed by X-ray diffraction. d value was 3.26, and it was confirmed that it was a single phase of rutile type crystal.

(Example 2)

197 g of pure water was placed in a 2 L vessel, 269 g of tin oxalate aqueous solution (containing 7.5 g in terms of SnO ₂ and 12.6 g in terms of oxalic acid) prepared in Production Example 1 and 142 g of titanium tetraisopropoxide (containing 40 g in terms of TiO ₂ ) 73 g of oxalic acid dihydrate (52 g in terms of oxalic acid) and 319 g of 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.4, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 1000 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours and maintained at a reduced pressure of 580 Torr for 2 hours. Then, pure water was used to adjust the TiO ₂ -converted concentration to 4.0% by mass. The titanium-containing aqueous solution thus obtained had a pH of 5.1 and a conductivity of 30.9 mS / cm. 1000 g of the titanium-containing aqueous solution after the above concentration adjustment was added to a 3 L glass-lined autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The resulting sol had a particle diameter of 16 nm as measured by a dynamic light scattering method, a pH of 3.9, a conductivity of 32.6 mS / cm, a concentration of 4.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 8.0 mass%, an oxalic acid concentration of 6.5 mass% On microscopic observation, elliptical particles of 5 nm in short axis and 15 nm in long axis were observed. The obtained sol was dried at 110 占 폚 and the powder obtained was analyzed by X-ray diffraction. d value was 3.26, and it was confirmed that it was a single phase of rutile type crystal. 1000 g of the rutile titanium oxide aqueous sol was concentrated using a rotary evaporator to obtain a stable rutile titanium oxide aqueous sol having a concentration of 20.5 mass% in terms of TiO ₂ . The particle diameter measured according to the dynamic light scattering method was 16 nm.

(Example 3)

44.9 g of pure water was added to 200 mL of a beaker, and 26.9 g (0.75 g in terms of SnO ₂ , containing 1.26 g in terms of oxalic acid) of the aqueous tin oxalate solution prepared in Preparation Example 1 and 14.2 g of titanium tetraisopropoxide in terms of TiO ₂ (1.6 g in terms of oxalic acid) and 11.8 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 0.63, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 0.65. 100 g of the titanium-containing aqueous solution was heated at 80 DEG C for 2 hours. The pH of the titanium-containing aqueous solution after heating was 3.6, the conductivity was 15.8 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 mL Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a pH of 3.4, a conductivity of 18.0 mS / cm, a concentration of 4.0% by mass in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 3.0% by mass, a concentration of oxalic acid of 2.9% by mass, a particle diameter of 22 nm as measured by a dynamic light scattering method, On microscopic observation, elliptical particles of 5 nm in short axis and 15 nm in long axis were observed. The obtained sol was dried at 110 占 폚 and the powder obtained was analyzed by X-ray diffraction. The value of d was 3.29, and it was confirmed that it was a single phase of a rutile type crystal.

(Example 4)

Put 3.5g of pure water to a beaker of 200mL, tin oxalic acid aqueous solution prepared in Preparation Example 1 26.9g (SnO ₂ converted to 0.75g, oxalic acid converted to contain 1.26g), titanium tetraisopropoxide 14.2g (TiO ₂ converted to 4.0 ), 9.8 g of oxalic acid dihydrate (7.0 g in terms of oxalic acid) and 45.6 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.8, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 2.5. 100 g of the titanium-containing aqueous solution was heated at 90 캜 for 2 hours. The pH of the titanium-containing aqueous solution after heating was 4.9, the conductivity was 37.4 mS / cm, and the concentration in terms of TiO ₂ was 4.0 mass%. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a particle diameter of 17 m measured by a dynamic light scattering method at a pH of 4.2, a conductivity of 41.0 mS / cm, a concentration of 4.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 11.4 mass%, an oxalic acid concentration of 8.3 mass% On microscopic observation, elliptical particles of 5 nm in short axis and 20 nm in long axis were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a single phase of a rutile crystal.

(Example 5)

(Containing 1.1 g in terms of SnO ₂ and 1.8 g in terms of oxalic acid), 2.8 g of titanium tetraisopropoxide (0.79 g in terms of TiO ₂ ), and 30 g of pure water in a 200 mL beaker, (0.45 g in terms of oxalic acid) and 7.3 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The obtained titanium-containing aqueous solution had a molar ratio of tin atom / titanium atom of 0.7, a molar ratio of oxalic acid / titanium atom of 2.5, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 79.0 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours. The pH of the titanium-containing aqueous solution after heating was 3.2, the conductivity was 18.3 mS / cm, and the concentration in terms of TiO ₂ was 1.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a pH of 3.2, a conductivity of 14.5 mS / cm, a TiO ₂ concentration of 1.0% by mass, a tetramethylammonium hydroxide concentration of 2.3% by mass, an oxalic acid concentration of 2.3% by mass, a particle diameter of 14 nm as measured by a dynamic light scattering method, In the microscopic observation, aggregated particles of 15 to 30 nm in which particles having a primary particle diameter of about 5 nm were aggregated were observed. The obtained sol was dried at 110 占 폚 and the powder obtained was analyzed by X-ray diffraction. The value of d was 3.34, confirming that it was a single phase of a rutile type crystal.

(Example 6)

19.7 g of pure water was added to 200 mL of a beaker, and 26.9 g (0.75 g in terms of SnO ₂ , containing 1.26 g in terms of oxalic acid) of the aqueous tin oxalate solution prepared in Preparation Example 1 and 14.2 g of titanium tetraisopropoxide (4.0 in terms of TiO ₂₎ g), oxalic acid dihydrate (5.2 g in terms of oxalic acid), and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.4, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 100 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours, maintained at a reduced pressure of 580 Torr for 2 hours, and then adjusted to pure water to have a TiO ₂ reduced concentration of 4.0% by mass. The obtained titanium-containing aqueous solution had a pH of 5.1, a conductivity of 30.9 mS / cm, and a concentration in terms of TiO ₂ of 4.0% by mass. 60 g of the titanium-containing aqueous solution after the concentration adjustment described above was charged into a 100 mL Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 100 DEG C for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a pH of 4.4, a conductivity of 32.1 mS / cm, a concentration of 4.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 8.0 mass%, a concentration of oxalic acid of 6.5 mass%, a particle diameter of 19 nm measured by a dynamic light scattering method, In the microscopic observation, elliptical particles of about 10 nm were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a single phase of a rutile crystal.

(Example 7)

19.7 g of pure water was added to 200 mL of a beaker, and 26.9 g (0.75 g in terms of SnO ₂ , containing 1.26 g in terms of oxalic acid) of the aqueous tin oxalate solution prepared in Preparation Example 1 and 14.2 g of titanium tetraisopropoxide (4.0 in terms of TiO ₂₎ g), oxalic acid dihydrate (5.2 g in terms of oxalic acid), and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.4, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. The titanium-containing aqueous solution (100 g) was heated at 80 캜 for 2 hours, maintained at a reduced pressure of 580 Torr for 2 hours, and then pure water was used so that the concentration in terms of TiO ₂ became 4.0% by mass. The obtained titanium-containing aqueous solution had a pH of 5.1, a conductivity of 30.9 mS / cm, and a concentration in terms of TiO ₂ of 4.0% by mass. 100 g of the titanium-containing aqueous solution after the above concentration adjustment was introduced into an SUS product autoclave vessel of 200 mL, and hydrothermal treatment was performed at 180 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The obtained sol, pH 6.9, conductivity of 41.6mS / cm, in terms of TiO ₂ concentration of 4.0% by mass, and a particle size of 81nm measured according to tetramethylammonium hydroxide concentration of 8.0% by mass oxalic acid concentration of 6.5% by mass, a dynamic light scattering method, a transmission electron In the microscopic observation, elliptical particles of about 20 nm were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a single phase of a rutile crystal.

(Production Example 2)

20 g of pure water was added to 100 mL of the beaker, and sodium tartrate [containing 51.7% by mass as SnO ₂ , Showa Kako Corp. Product] was dissolved. Subsequently, the solution was passed through a column packed with a small-sized cation exchange resin (Amberlite (registered trademark) IR-120B) to remove sodium, and 45.2 g of an aqueous tartaric acid solution having a concentration of 1.6 wt% in terms of SnO ₂ was prepared. As a result of the atomic absorption analysis, the concentration of sodium in the aqueous tartaric acid solution was 6 ppm.

(Comparative Example 1)

(Containing 0.72 g in terms of SnO ₂ ), 14.2 g (containing 4.0 g in terms of TiO ₂ ) of titanium tetraisopropoxide, 0.5 g of oxalic acid dihydrate (5.6 g in terms of oxalic acid) and 30.6 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The obtained titanium-containing aqueous solution had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.3, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 95.9 g of the titanium-containing aqueous solution was heated at 80 占 폚 for 2 hours. The pH of the titanium-containing aqueous solution after heating was 5.9, the conductivity was 31.5 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The obtained sol, pH 3.9, conductivity of 36.0mS / cm, in terms of TiO ₂ concentration of 4.0% by mass, and a particle size of 17nm measured according to tetramethylammonium hydroxide concentration of 8.0% by mass oxalic acid concentration of 5.8% by mass, a dynamic light scattering method, a transmission electron On the microscopic observation, circular particles having a diameter of about 5 nm and elliptical particles having a minor axis of 5 nm and a major axis of 25 nm were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a mixture of anatase type crystal and rutile type crystal.

(Comparative Example 2)

19.7 g of pure water was added to a 200 mL beaker and 17.7 g of an isopropanol solution of 10 mass% tin (IV) isopropoxide (containing 0.75 g in terms of SnO ₂ ) (manufactured by Alfa Aesar), 14.2 g of titanium tetraisopropoxide (Containing 4.0 g in terms of TiO ₂ ), 9.5 g of oxalic acid dihydrate (6.7 g in terms of oxalic acid) and 36.4 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.5, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 2.0. 100 g of the titanium-containing aqueous solution was heated at 90 캜 for 2 hours. The pH of the titanium-containing aqueous solution after heating was 4.7, the conductivity was 28.6 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The obtained sol, pH 3.9, and the conductivity of 31.4mS / cm, in terms of TiO ₂ concentration of 4.0% by mass, a particle size of 16nm measured according to tetramethylammonium hydroxide concentration of 9.1% by mass oxalic acid concentration of 6.7% by mass, a dynamic light scattering method, a transmission electron On microscopic observation, rounded particles of 5 nm and oval particles of 5 nm of short axis and 20 nm of long axis were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a mixture of anatase type crystal and rutile type crystal.

(Comparative Example 3)

(Containing 0.38 g in terms of SnO ₂ and 0.63 g in terms of oxalic acid) and 7.1 g of titanium tetraisopropoxide (converted to 2.0 in terms of TiO ₂ ) were put into a beaker of 200 mL, to which 74.7 g of pure water was added, g), 4.2 g of oxalic acid dihydrate (3.0 g in terms of oxalic acid), and 63.8 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The obtained titanium-containing aqueous solution had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.6, and a molar ratio of tetramethylammonium hydroxide / oxalic acid of 7.0. 100 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours, maintained at a reduced pressure of 580 Torr for 2 hours, and then adjusted to pure water to have a TiO ₂ reduced concentration of 4.0% by mass. The pH of the titanium-containing aqueous solution after the adjustment was 14.6, the conductivity was 62.1 mS / cm, and the concentration in terms of TiO ₂ was 2.0% by mass. 60 g of the titanium-containing aqueous solution after the above concentration adjustment was introduced into a 100 mL Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After cooling to room temperature, the obtained solution after the treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a pH of 14.0, a conductivity of 50.0 mS / cm, a concentration of 2.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 15.9 mass%, a concentration of oxalic acid of 3.6 mass%, a particle diameter of 115 nm measured by a dynamic light scattering method, Spherical particles having a diameter of about 20 nm and oval particles having a short axis of 70 nm and a long axis of 350 nm were observed under a microscope. The powder obtained by drying the obtained sol at 110 占 폚 was analyzed by X-ray diffraction to find that it was a mixture of a rutile crystal and a bourcite crystal.

(Comparative Example 4)

19.7 g of pure water was added to 200 mL of a beaker, and 26.9 g (0.75 g in terms of SnO ₂ , containing 1.26 g in terms of oxalic acid) of the aqueous tin oxalate solution prepared in Preparation Example 1 and 14.2 g of titanium tetraisopropoxide (4.0 in terms of TiO ₂₎ g), oxalic acid dihydrate (5.2 g in terms of oxalic acid), and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 1.4, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 100 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours, maintained at a reduced pressure of 580 Torr for 2 hours, and then adjusted to pure water to have a TiO ₂ reduced concentration of 4.0% by mass. The pH of the titanium-containing aqueous solution after the adjustment was 5.1, the conductivity was 30.9 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 100 g of the titanium-containing aqueous solution after the above concentration adjustment was introduced into a 200-mL SUS product autoclave vessel, and hydrothermal treatment was performed at 220 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a milky white suspension. The obtained suspension had a particle diameter of 950 nm as measured by a dynamic light scattering method at pH 8.2, conductivity of 42.0 mS / cm, concentration of 4.0 mass% in terms of TiO ₂ , concentration of tetramethylammonium hydroxide of 8.0 mass%, concentration of oxalic acid of 6.5 mass% In the microscopic observation, agglomerates of colloidal particles having a primary particle diameter of about 5 nm aggregated and became 500 nm or more were observed. The resulting suspension was dried at 110 占 폚 and the powder thus obtained was subjected to X-ray diffraction analysis to confirm that it was a rutile crystal.

(Comparative Example 5)

(Containing 0.38 g in terms of SnO ₂ and 0.63 g in terms of oxalic acid) and 14.2 g of titanium tetraisopropoxide (4.0 in terms of TiO ₂ ) were added to a 200-mL beaker, to which 32.2 g of pure water was added, g), oxalic acid dihydrate (5.5 g in terms of oxalic acid), and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.05, a molar ratio of oxalic acid / titanium atom of 1.4, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 100 g of the titanium-containing aqueous solution was heated at 80 DEG C for 2 hours. The pH of the titanium-containing aqueous solution after heating was 4.7, the conductivity was 29.4 mS / cm, and the concentration in terms of TiO ₂ was 4.0 mass%. 100 g of the titanium-containing aqueous solution after heating was charged into a 200-mL SUS product autoclave vessel, and hydrothermal treatment was performed at 180 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a pH of 3.9, a conductivity of 32.0 mS / cm, a concentration of 4.0% by mass in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 8.0% by mass, a concentration of oxalic acid of 6.5% by mass, a particle diameter of 22 nm as measured by a dynamic light scattering method, On microscopic observation, elliptical particles of 5 nm in short axis and 20 nm in long axis were observed. The powder obtained by drying the obtained sol at 110 占 폚 was analyzed by X-ray diffraction to find that it was a mixture of rutile type crystals and anatase type crystals.

(Comparative Example 6)

(Containing 0.38 g in terms of SnO ₂ and 0.63 g in terms of oxalic acid) and 7.2 g of titanium tetraisopropoxide (2.0 in terms of TiO ₂ ) were added to 200 mL of the beaker, (15.3 g in terms of oxalic acid) and 18.2 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1, a molar ratio of oxalic acid / titanium atom of 7.1, and a molar ratio of tetramethylammonium hydroxide / titanium atom of 2.0. 100 g of the titanium-containing aqueous solution was heated at 80 캜 for 2 hours, maintained at a reduced pressure of 580 Torr for 2 hours, and then adjusted to pure water to have a TiO ₂ reduced concentration of 4.0% by mass. The obtained titanium-containing aqueous solution had a pH of 2.1, a conductivity of 93.5 mS / cm, and a concentration in terms of TiO ₂ of 2.0% by mass. 60 g of the titanium-containing aqueous solution after the above concentration adjustment was introduced into a 100 mL Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a milky white suspension. The suspension thus obtained had a pH of 2.1, a conductivity of 27.0 mS / cm, a concentration of 2.0% by weight in terms of TiO ₂ , a concentration of 2.3% by mass of tetramethylammonium hydroxide, a concentration of oxalic acid of 15.9% by mass, a particle diameter of 243 nm measured by a dynamic light scattering method, In the microscopic observation, aggregates having aggregated colloidal particles having a primary particle diameter of about 4 nm and having a particle size of 300 nm or more were observed. The resulting suspension was dried at 110 占 폚 and the powder thus obtained was subjected to X-ray diffraction analysis to confirm that it was a rutile crystal.

(Comparative Example 7)

36.2 g of pure water was added to a 200 mL beaker and 17.7 g of a 10 mass% tin (IV) isopropoxide isopropanol solution (manufactured by Alfa Aesar) (containing 0.75 g in terms of SnO ₂ ) and 14.2 g of titanium tetraisopropoxide Containing 4.0 g in terms of TiO ₂ ) and 31.9 g of a 25 mass% aqueous solution of tetramethylammonium hydroxide were added with stirring. The titanium-containing aqueous solution obtained had a molar ratio of tin atom / titanium atom of 0.1 and a molar ratio of tetramethylammonium hydroxide / titanium atom of 1.75. 100 g of the titanium-containing aqueous solution was heated at 90 캜 for 2 hours. The pH of the titanium-containing aqueous solution after heating was 14, the conductivity was 64.9 mS / cm, and the concentration in terms of TiO ₂ was 4.0% by mass. 60 g of the titanium-containing aqueous solution after heating was charged into a 100 ml Teflon (registered trademark) product autoclave vessel, and hydrothermal treatment was performed at 140 캜 for 5 hours. After hydrothermal treatment, it was cooled to room temperature. The solution after the hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The sol thus obtained had a particle size of 125 nm measured by a dynamic light scattering method at a pH of 14, a conductivity of 67.4 mS / cm, a concentration of 4.0 mass% in terms of TiO ₂ , a concentration of tetramethylammonium hydroxide of 9.1 mass% Of spherical particles were observed. The powder obtained by drying the obtained sol at 110 占 폚 was subjected to an X-ray diffraction analysis to confirm that it was a mixture of anatase type crystal and rutile type crystal.

[Table 1]

NR ₄ (OH) (*): Quaternary ammonium hydroxide

Particle diameter (nm) (**): Measured according to dynamic light scattering method

The rutile-type titanium oxide sol obtained by the present invention is useful as a catalyst, a photocatalyst, an optical material, an antibacterial agent, and a pollution prevention, and is particularly useful as a titanium oxide for a transparent electrode of a dye-sensitized solar cell.

Claims (4)

A process for producing a rutile titanium oxide sol having a particle diameter of 5 to 100 nm, which is measured by a dynamic light scattering method including the following steps (a) and (b):
(a) Process: A tin oxalate aqueous solution, a titanium alkoxide, oxalic acid, a quaternary ammonium hydroxide and water are mixed, and then 0.1 to 0.8 mol of tin atoms per mol of the titanium atom, 0.01 To 5 moles of said quaternary ammonium hydroxide and 0.1 to 3.5 moles of said quaternary ammonium hydroxide to prepare a titanium-containing aqueous solution having a concentration of 0.1 to 15 mass% in terms of TiO ₂ ,
(b) A step of hydrothermally treating the titanium-containing aqueous solution obtained in the step (a) at 100 to 200 캜.
The method according to claim 1,
Wherein the titanium alkoxide has the general formula (I)
_{^{Ti (OR 1) 4 (I}} )
Wherein each R ¹ in the formula (I) is the same or different and is an alkyl group having 1 to 3 carbon atoms.
The method according to claim 1,
Wherein the quaternary ammonium hydroxide is represented by the general formula (II)
[NR ² R ³ R ⁴ R ⁵ ] OH (II)
R ² , R ³ , R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group having 1 to 8 carbon atoms or an alkyl group having 7 to 15 carbon atoms An aryloxyalkyl group having 1 to 20 carbon atoms, or a benzyl group), which is a quaternary ammonium hydroxide.
The method of claim 3,
Wherein the quaternary ammonium hydroxide is tetramethylammonium hydroxide or tetraethylammonium hydroxide.